Chemical control of weed with herbicide(s) is a most economical and effective means for controlling weeds in farmlands. However, continuously use of a single chemical herbicide or chemical herbicides having a single functional mechanism at a high dosage for a long period of time is likely to cause problems associated with evolved drug resistance and tolerance of weeds. Well complexing or formulating of herbicidal compounds can achieve the following advantages: expanding weed spectrum, improving weed control effect, and delaying occurrence and development of drug resistance and tolerance of weeds, and thus is one of the most effective means to solve the above problems.
The hydroxyphenyl pyruvate dioxygenase (HPPD) inhibitor is another novel herbicide following the acetyl CoA carboxylase (ACCase) inhibitor, the acetolactate synthase (ALS) inhibitor and the Protox inhibitor etc. The HPPD inhibitor has a broad spectrum of herbicidal activity, can be used before and after budding, and may cause albinism and death of weeds. Although the HPPD inhibitor result in similar poisoning symptoms to that of carotenoid bio-inhibitors, it is markedly different from the known carotenoid bio-inhibitors in terms of chemical properties such as polarity and ionization degree etc. . . . . The risk of resistance of weeds to HPPD inhibitor herbicides is significantly reduced compared to that of ACCase inhibitors and ALS inhibitors, and there is no cross target resistance resulted from a HPPD inhibitor and a common ALS inhibitor (e.g., tribenuron, bensulfuron-methyl, florasulam) which is usually used in wheat fields.
Herbicides, such as protoporphyrinogen oxidase (PPO) inhibitors, photosynthetic photosystem II herbicides and phytoene dehydrogenase (PDS) inhibitors, play an important role in a system for preventing the growth of weeds in wheat fields.
Conventional photosynthetic photosystem II herbicides in wheat fields comprise bromoxynil, octanoylbromobenzonitrile, iodobenzonitrile, bentazone, isoproturon, chlorotoluron, terbutryn, prometryn, metribuzin, and the like; photosynthetic photosystem II herbicides are selective contact herbicides acting on stems and leaves after budding, and mainly absorbed by the leaves and rapidly result in tissue necrosis by inhibiting each step in photosynthesis. The above herbicides can be used for controlling broad-leaved weeds in wheat fields, such as Sisymbrium sophia, Capsella bursa-pastoris, and Catchweed etc. However, when this class of herbicides is used alone, a high dosage is needed, and the wheat is at serious safety risk. If they are used at a low dosage, the weed control effect is poor. Therefore, it is required strict application technique and dosage. There is no cross target resistance resulted from a photosynthetic photosystem II herbicide and a common ALS inhibitor (e.g., tribenuron, bensulfuron-methyl, florasulam) which is usually used in wheat fields.
Conventional phytoene dehydrogenase (PDS) inhibitors in wheat fields comprise diflufenican, picolinafen, and the like. This class of herbicides belongs to carotenoid biosynthetic inhibitors, which lead to chlorophyll damage and cell rupture, and plant death, is a broad-spectrum selective herbicides in wheat fields and suitable for controlling broad-leaved weeds in barley and wheat fields, such as Sisymbrium sophia, Capsella bursa-pastoris, Catchweed, and Myosoton aquaticum etc. However, when this class of agents is used alone, a high dosage is needed, and the wheat is at serious safety risk. If they are used at a low dosage, the weed control effect is poor. Therefore, it is required strict application technique and dosage. There is no cross target resistance resulted from a PDS inhibitor and a common ALS inhibitor (e.g., tribenuron, bensulfuron-methyl, florasulam) which is usually used in wheat fields.